<template>
  <div class="pagination">
    <button :disabled="pageNo <= 1" @click="$emit('changePage', pageNo - 1)">
      上一页
    </button>
    <button v-show="ContinueStartEnd.start > 1" @click="$emit('changePage', 1)">
      1
    </button>

    <button v-show="ContinueStartEnd.start > 2">···</button>

    <button
      v-for="page in showPages"
      :key="page"
      :class="{ active: page === pageNo }"
      @click="$emit('changePage', page)"
    >
      {{ page }}
    </button>

    <button v-show="ContinueStartEnd.end < totalPages - 1">···</button>
    <button
      v-show="ContinueStartEnd.end < totalPages"
      @click="$emit('changePage', totalPages)"
    >
      {{ totalPages }}
    </button>
    <button
      :disabled="pageNo >= totalPages"
      @click="$emit('changePage', pageNo + 1)"
    >
      下一页
    </button>

    <button style="margin-left: 30px">共 {{ total }} 条</button>
  </div>
</template>

<script>
export default {
  name: "Pagination",
  props: ["total", "totalPages", "pageNo", "continuePages"],
  computed: {
    ContinueStartEnd() {
      const { totalPages, pageNo, continuePages } = this;
      let start = 0,
        end = 0;
      start = pageNo - Math.floor(continuePages / 2);
      end = pageNo + Math.floor(continuePages / 2);

      if (start < 1) {
        start = 1;
        end = continuePages;
      }
      if (end > totalPages) {
        end = totalPages;
        start = totalPages - continuePages + 1;
      }

      return { start, end };
    },
    showPages() {
      const { start, end } = this.ContinueStartEnd;
      let arr = [];
      for (let i = 1; i <= end; i++) {
        if (i >= start) arr.push(i);
      }
      return arr;
    },
  },
};
</script>

<style lang="less" scoped>
.pagination {
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }
  }
}
</style>
